Reconstruction of fatigue crack growth in aluminum lithium and aluminum copper fastened lap joints under marker band loading

•A fatigue crack growth reconstruction methodology using marker bands on the fatigue fracture surface was adopted to capture a snapshot of fatigue crack growth behavior in two different aluminum alloys.•Aluminum-lithium alloys exhibited different fatigue fracture morphologies depending on the direct...

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Bibliographic Details
Published in:International journal of fatigue 2017-10, Vol.103, p.516-532
Main Authors: Stanley, David, Awerbuch, Jonathan, Tan, Tein-Min
Format: Article
Language:English
Subjects:
Alloying effects
Aluminum
Aluminum alloys
Aluminum base alloys
Aluminum-lithium alloy
Crack growth reconstruction
Crack initiation
Crack propagation
Cracks
Data reduction
Fastened lap joint
Fatigue failure
Fractography
Fracture mechanics
Lap joints
Lithium
Marker bands
Materials fatigue
Rolling direction
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Summary:•A fatigue crack growth reconstruction methodology using marker bands on the fatigue fracture surface was adopted to capture a snapshot of fatigue crack growth behavior in two different aluminum alloys.•Aluminum-lithium alloys exhibited different fatigue fracture morphologies depending on the direction of crack growth relative to the stacking direction of the materials elongated grains.•Both materials show cracking on the plane of the fracture surface with cracks being consistently located at the change in R-ratio used to generate the marker bands. A comparative study on the fatigue crack growth behavior in a typical third generation Al/Li alloy (AA2198-T8) and traditional aerospace aluminum alloy (AA2024-T3) was conducted. Fatigue crack growth history was reconstructed using marker band loading sequences (i.e., applying two different R-ratios). Effect of alloying and loading direction (relative to the rolling direction) was discerned from the fatigue fracture surface morphologies, which were markedly different in the two alloys. The marker band imprints aided in identifying suspected fatigue crack initiation region and estimating crack growth rate. A data reduction scheme was used to estimate crack initiation cycle.
ISSN:0142-1123
1879-3452
DOI:10.1016/j.ijfatigue.2017.06.027